Many different entities consume fresh water resources including farming, municipalities for drinking water, industrial companies, and residences. As population and urbanization increases, the demand from these entities on fresh water resources further increases, thereby making conservation and efficient use of fresh water critical. One common problem is the frequent over use of water. For example, sprinkler systems running during or immediately after rain or during freezing temperatures, resulting in the waste of large quantities of water and dangerous conditions due to ice formation.
Recently, agricultural and residential uses of water have become the focus of conservation and efficiency efforts. For example, local municipalities have implemented watering restrictions and in some places entire watering bans. Various types of equipment have been developed to limit watering, including automatic timers, rain sensors, and freeze sensors, which control an entire sprinkler system. However, a typical residential yard includes grass, shrubs, and trees, each of which requires different watering amounts to remain healthy. These solutions do not account for these different levels of watering needs, leading to the death of plants and soil erosion, which contaminates water supplies only making such resources more scarce.
The prior art has attempted to solve these problems with limited success. For example, U.S. Pat. No. 6,978,794 to Dukes discloses an automatic control system and method for irrigation. The system includes a control device connected to an irrigation structure to control the water flow. A set of time domain reflectometry sensors is connected to the control device to measure moisture in the soil. The control device determines whether to irrigate the soil based on the measurements received from the set of time domain reflectometry sensors. If needed, the control device activates the irrigation structure to irrigate the soil. However, the system in Dukes requires the time domain reflectometry sensors to be buried at different depths in order to measure moisture, thereby leading to inaccurate measurements. Further, the system in Dukes cannot generate a three dimensional resistivity model.
U.S. Pat. No. 7,063,271 to Lashgari discloses a moisture responsive sprinkler circuit. The sprinkler circuit includes a control circuit and a moisture responsive circuit. The control circuit is connected between a sprinkler controller (e.g., timer) and a sprinkler valve, and is powered by a valve signal sent from the sprinkler controller to the valve. The moisture responsive circuit includes two pairs of electrodes wired in series and residing at different depths. When resistance across both pairs of electrodes drops sufficiently, a relay in the control circuit opens and interrupts the valve signal to the valve to control irrigation. However, the pair of electrodes must be placed at different depths that depend on the root depth of a plant in order to work properly resulting in time consuming installation. Further, because the root depth changes as the plant grows, the electrodes are easily misaligned with the root depth leading to inaccurate measurements.
U.S. Pat. No. 8,671,969 to Dresselhaus discloses a moisture sensor buried in the soil that measures a moisture level of the surrounding soil. Each watering zone within an irrigation system has a moisture sensor buried in the soil to individually monitor and determine how much water is needed in each zone. The moisture sensor includes control functionality and acts as a regulator for the watering zone in which the moisture sensor is located. The moisture sensor regulates the amount of water the zone receives by preventing actuation of a solenoid valve based upon a moisture level reading. The moisture sensor is coupled between an irrigation controller and the solenoid valve. Once supplied power from the irrigation controller, the moisture sensor supplies power to the solenoid valve so long as the moisture level of the soil is not above a threshold level. The power to the solenoid valve actuates the solenoid valve and allows water to flow to sprinklers. However, the sensor in Dresselhaus does not account for different vegetation within each zone and thereby can still lead to overwatering or underwatering within each zone.
Therefore, there is a need in the art for a system that measures soil moisture at different depths in three dimensions. There is a further need for a system and method for controlling a sprinkler system based on plant moisture requirements. There is still a further need for a system and method for controlling a sprinkler system based on a three-dimensional moisture model.